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Add new flag to format_type_extended() to get NULL for undefined type 

If a type scanned is undefined, type format routines have two behaviors
depending on if FORMAT_TYPE_ALLOW_INVALID is used by the caller or not:
- Issue a cache lookup error
- Return an undefined type name "???", "???[]" or "-"

The current interface is not really helpful for callers willing to
format properly a type name, but still make sure that the type is
defined as there could be types matching the strings generated when
looking for an undefined type, even if that should not be a problem in
practice.  In order to counter that, add a new flag called
FORMAT_TYPE_INVALID_AS_NULL that returns a NULL result instead of "???
or "-" which does not generate an error.  This flag will be used in a
follow-up patch improving the set of SQL functions showing information
for object addresses when it comes to undefined objects.

Author: Michael Paquier
Reviewed-by: Aleksander Alekseev, Dmitry Dolgov, Daniel Gustafsson,
Álvaro Herrera
Discussion: https://postgr.es/m/CAB7nPqSZxrSmdHK-rny7z8mi=EAFXJ5J-0RbzDw6aus=wB5azQ@mail.gmail.com
This commit is contained in:
Michael Paquier 2020-07-06 12:12:11 +09:00
parent 231ef5b90d
commit 1185c78294
2 changed files with 18 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
src/backend/utils/adt/format_type.c
View File

@ -96,13 +96,16 @@ format_type(PG_FUNCTION_ARGS)
* - FORMAT_TYPE_ALLOW_INVALID
* if the type OID is invalid or unknown, return ??? or such instead
* of failing
* - FORMAT_TYPE_INVALID_AS_NULL
* if the type OID is invalid or unknown, return NULL instead of ???
* or such
* - FORMAT_TYPE_FORCE_QUALIFY
* always schema-qualify type names, regardless of search_path
*
* Note that TYPEMOD_GIVEN is not interchangeable with "typemod == -1";
* see the comments above for format_type().
*
* Returns a palloc'd string.
* Returns a palloc'd string, or NULL.
*/
char *
format_type_extended(Oid type_oid, int32 typemod, bits16 flags)
@ -114,13 +117,20 @@ format_type_extended(Oid type_oid, int32 typemod, bits16 flags)
char *buf;
bool with_typemod;
if (type_oid == InvalidOid && (flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
return pstrdup("-");
if (type_oid == InvalidOid)
{
if ((flags & FORMAT_TYPE_INVALID_AS_NULL) != 0)
return NULL;
else if ((flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
return pstrdup("-");
}
tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(type_oid));
if (!HeapTupleIsValid(tuple))
{
if ((flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
if ((flags & FORMAT_TYPE_INVALID_AS_NULL) != 0)
return NULL;
else if ((flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
return pstrdup("???");
else
elog(ERROR, "cache lookup failed for type %u", type_oid);
@ -144,7 +154,9 @@ format_type_extended(Oid type_oid, int32 typemod, bits16 flags)
tuple = SearchSysCache1(TYPEOID, ObjectIdGetDatum(array_base_type));
if (!HeapTupleIsValid(tuple))
{
if ((flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
if ((flags & FORMAT_TYPE_INVALID_AS_NULL) != 0)
return NULL;
else if ((flags & FORMAT_TYPE_ALLOW_INVALID) != 0)
return pstrdup("???[]");
else
elog(ERROR, "cache lookup failed for type %u", type_oid);

1
src/include/utils/builtins.h
View File

@ -113,6 +113,7 @@ extern Datum numeric_float8_no_overflow(PG_FUNCTION_ARGS);
#define FORMAT_TYPE_TYPEMOD_GIVEN 0x01 /* typemod defined by caller */
#define FORMAT_TYPE_ALLOW_INVALID 0x02 /* allow invalid types */
#define FORMAT_TYPE_FORCE_QUALIFY 0x04 /* force qualification of type */
#define FORMAT_TYPE_INVALID_AS_NULL 0x08 /* NULL if undefined */
extern char *format_type_extended(Oid type_oid, int32 typemod, bits16 flags);
extern char *format_type_be(Oid type_oid);